#include <iostream>
#include <fstream>
#include <vector>
#include <string>
#include <algorithm>
using namespace std;
#define REP(i,n) for(int i = 0; i < (n); i++)

int main(){


		string s; cin>>s;
		int a=s.size();
		int b[3] = {};
		REP(i,a){
				if (s[i] == 't') {
						b[0]++;
				}else if (s[i] == 'r') {
						b[1]++;
				}else if (s[i] == 'e') {
						b[2]++;
				}
		}
		int c = min(b[0],min(b[1],(b[2] / 2)));
		cout << c<<"\n";
		return 0;
}